Hello Everyone! My name's Pascal, 19 from Austria and I'm into collecting and repairing Vintage Electronics. My uncle recently got me a Sony WM-D6C (my dream walkman), which he found at a flea market. It's in beautiful condition externally, some of the accessories are still in their original packaging. Unfortunately it's running too fast . I guess it's an earlier model, because the pcb uses through-hole components. The previous owner already tried fixing the motor controller chip, but that didn't help anything. (I still have the original though) So now I'm asking for help here, because my electronic skills are pretty limited, despite visiting a school for electronic engineering for 4 years . Greetings Pascal
This is a known fault when the wrong power supply / polarity has been used at some point. Either wait or send a PM to Deb64, she is our resident expert. I am sure she can tell you how to fix it.
Welcome to S2G DerGotai as TooCooL4 mentioned wait for Deb64 to get your answer, meantime see these posts: http://www.stereo2go.com/forums/thr...fast-repair-of-cp602-servo-circuit-unit.1853/ http://stereo2go.com/forums/threads/sony-wm-d6c-playing-too-fast.2960/
Hello Pascal and welcome to Stereo2go. There are a few possible reasons why your D6C is still running fast after having a new CX20084 IC fitted. I would need to have the walkman on the bench in front of me to be able to find the problem but there are few things you can check. Firstly, it is possible that the previous owner fitted a fake IC - there are a few of these around. Check that you have B+ (6V) on pin 8 and 0V on pin 16. Then check if you have 1.65V on pin 5. This is a reference voltage generated by the chip's internal regulator. If you have a useless lump of plastic, you won't find 1.65V on pin 5. Check that the pins have been soldered to the pads correctly. I had a D6C in for repair where the owner had tried to replace the CX20084 and it was still running fast. All it needed was the solder joints on the pins re-touching. Lastly, check that the wires have been soldered back in the correct place, using the PCB layout in the service manual. Check that all the solder joints are secure. Especially, check the screened two core cable (red and white) which runs from the speed tune switch to the pads near the IC. Good luck.
Don't forget about checking the motor driver transistor (Q601 iirc). Incorrect polarity PSU can damage it in 2 ways, either make it short or go open. In your case it could be shorted, which also would cause the speed to be too fast.
Thank you all for your kind replies and suggestions, on what might be the fault with this WM-D6C! I'm pretty busy right now and only home on weekends, so the time I can work on the Walkman is quite limited So, I measured around, on what Deb wrote and I got the following results: 4V on pin 8 100mV on pin 16 But 1,6V on pin 5 I've checked with a magnifying glass and resoldered all the pins very carefully. I might've ripped off a brown wire near the battery terminal, but managed to solder it back in the right place. Those appear to be fine, but the speed tune switch and potentiometer seem to do absolutely nothing. So, what else could I try? -Pascal Here's a pic of the CX20084:
If you have the 1.6V on pin 5 of the IC, that is looking hopeful. One thing I can see straight away in your picture is the very bad corrosion and what look like dry solder joints in the area just above the notch between RV601 and RV603. This could be due to battery leakage or excessive soldering flux which has been spilled on the PCB. There is also spillage on the board in the area between IC301 and the motor, which needs to be cleaned off. You will need to desolder the dry joints and re-tin the component leads and pads to make good joints. Also, check the continuity of the tracks in that area as these may have been damaged by corrosion. If any tracks are open circuit, you may need to fit a wire bridge. Use good quality 60/40 tin/lead solder when you re-make the joints.
Yeah there was some Battery leakage. What's the best way to clean off the corrosion? Isopropyl alcohol, contact cleaner or brake cleaner?
I normally use a small paintbrush and 99% IPA to clean the corrosion off. You may need to use a scalpel to scrape the oxidisation off the pads and component leads before you can tin them and re-solder them. Also, check the electrolytic capacitors on the other side of the board for any signs of leakage. If in doubt, replace them.
Have you bridged these two pins? The Walkman will run twice as fast and not react to the speed control as well as run without pressing play if those points are not bridged.
Which points do you mean? The pad with the blue wire on is connected to pin 9 of IC601 but it should not connect to pin 10.
Yes, I mean it should be connected to pin 9. I had a problem exactly like this with the Walkman running twice as fast after a new driver transistor and IC and the issue was no continuity between that blue wire and pin 9.
